Removing Metal from Rails 3.

If you have existing Metals, you have a few options:
* if your metal behaves like a middleware, add it to the
  middleware stack via config.middleware.use. You can use
  methods on the middleware stack to control exactly where
  it should go
* if it behaves like a Rack endpoint, you can link to it
  in the router. This will result in more optimal routing
  time, and allows you to remove code in your endpoint
  that matches specific URLs in favor of the more powerful
  handling in the router itself.

For the future, you can use ActionController::Metal to get
a very fast controller with the ability to opt-in to specific
controller features without paying the penalty of the full
controller stack.

Since Rails 3 is closer to Rack, the Metal abstraction is
no longer needed.

1 files changed, 0 insertions, 51 deletions

diff --git a/railties/guides/source/rails_on_rack.textile b/railties/guides/source/rails_on_rack.textile
index 512be43668..eaebb05f17 100644
--- a/railties/guides/source/rails_on_rack.textile
+++ b/railties/guides/source/rails_on_rack.textile
@@ -222,57 +222,6 @@ use MyOwnStackFromStratch
 run ActionController::Dispatcher.new
 </ruby>
 
-h3. Rails Metal Applications
-
-Rails Metal applications are minimal Rack applications specially designed for integrating with a typical Rails application. As Rails Metal Applications skip all of the Action Controller stack, serving a request has no overhead from the Rails framework itself. This is especially useful for infrequent cases where the performance of the full stack Rails framework is an issue.
-
-Ryan Bates' "Railscast on Rails Metal":http://railscasts.com/episodes/150-rails-metal provides a nice walkthrough generating and using Rails Metal.
-
-h4. Generating a Metal Application
-
-Rails provides a generator called +metal+ for creating a new Metal application:
-
-<shell>
-$ rails generate metal poller
-</shell>
-
-This generates +poller.rb+ in the +app/metal+ directory:
-
-<ruby>
-# Allow the metal piece to run in isolation
-require(File.dirname(__FILE__) + "/../../config/environment") unless defined?(Rails)
-
-class Poller
-  def self.call(env)
-    if env["PATH_INFO"] =~ /^\/poller/
-      [200, {"Content-Type" => "text/html"}, ["Hello, World!"]]
-    else
-      [404, {"Content-Type" => "text/html", "X-Cascade" => "pass"}, ["Not Found"]]
-    end
-  end
-end
-</ruby>
-
-Metal applications within +app/metal+ folders in plugins will also be discovered and added to the list.
-
-Metal applications are an optimization. You should make sure to "understand the related performance implications":http://weblog.rubyonrails.org/2008/12/20/performance-of-rails-metal before using it.
-
-WARNING: To continue the Metal chain execution, return an +X-Cascade+ HTTP header with a value of +pass+.
-
-h4. Execution Order
-
-All Metal Applications are executed in alphabetical order of their filenames, so +aaa.rb+ will come before +bbb.rb+ in the metal chain.
-
-You can override the default ordering in your environment. Simply add a line like the following to +config/application.rb+
-
-It is, however, possible to override the default ordering in your environment. Simply add a line like the following to +config/environment.rb+
-
-<ruby>
-config.metals = ["Bbb", "Aaa"]
-</ruby>
-
-Each string in the array should be the name of your metal class. If you do this then be warned that any metal applications not listed will not be loaded.
-
 h3. Resources
 
 h4. Learning Rack